Climate and monthly weather forecastThunder Bay, Canada
Climate and monthly weather forecast
The climate of Thunder Bay
Thunder Bay, preferably recognized for its harmonious blend of natural splendor, sits in the heart of Canada Under the lens of the Köppen Climate Classification, this city is categorized under the Dfb zone, disclosing it as a region with a humid continental climate, no dry season, and warm summer.Predominantly, Thunder Bay experiences a wide assortment of weather conditions throughout the year. The temperatures show significant fluctuation, with the lower limit falling to -20.6°C (-5.1°F) during the coldest months and soaring to a peak of 24.3°C (75.7°F) during the warmest periods of the year. Snowfall characterizes the colder months with a substantial deposit of up to 389mm (15.31"), whereas rainfall is eminent during the warmer months, peaking at 90mm (3.54") for the wettest month.
Several remarkable weather patterns emerge in Thunder Bay's climate. Specifically, the abundance of snow in the colder months, with the heaviest fall recorded in December, reaching 389mm (15.31"). The presence of rain is most pronounced from May to August, however, an absence from December to February is similarly noted.
The best time to visit Thunder Bay
Thunder Bay's climate opens a desirable window for visitors seeking to enjoy its scenic beauty. A favorable time to venture into this city falls between May and September. During this span, the weather is relatively warm, with temperatures ranging from 9.2°C (48.6°F) to 24.3°C (75.7°F). Moreover, visitors can also delight in an extended period of daylight that peaks at 16 hours in June. Simultaneously, cloud cover is minimal, accentuating the opportunity to enjoy the radiant sunshine, which is at its climax in June and July, offering 8.7 hours of sunshine daily.The worst time to visit Thunder Bay
Highly dependent on weather preferences, yet the harsh winters of Thunder Bay may deter some visitors. Specifically, the timeline from December to February poses the most challenging weather conditions, with temperatures dipping between -20.6°C (-5.1°F) to -5.5°C (22.1°F). Apart from the freezing temperatures, this period encounters a significant snowfall with accumulation reaching up to 389mm (15.31") in December. Furthermore, daylight hours are reduced to a minimal 8.4 hours in December.Spring weather in Thunder Bay
Spring in Thunder Bay carries weather conditions from bitter cold to mildly warm. March initiates the season with a cool -10.7°C (12.7°F), which gradually warms up to 16.2°C (61.2°F) by May. Concurrently, daylight hours extend noticeably from 11.9 hours in March to 15.3 hours in May. The arrival of spring also brings in substantial rainfall, proportionately increasing from 16mm (0.63") in March to 66mm (2.6") in May.Summer weather in Thunder Bay
The summer season in Thunder Bay, stretched from June through August, enjoys warm temperatures. The heat levels peak in July, with the mercury soaring to an average temperature of 24.3°C (75.7°F). Rainfall remains consistent throughout these months, hitting a high in August with 90mm (3.54"). Added the plentiful sunshine, averaging around 8.6 hours daily during peak summer, these months provide the opportune moment for outdoor activities.Autumn weather in Thunder Bay
With Autumn setting in, Thunder Bay witnesses temperatures sliding from 17.7°C (63.9°F) in September to a chilly 1.4°C (34.5°F) in November. As daylight reduces from 12.6 hours in September to 9.2 hours in November, sunshine hours simultaneously drop from 5.5 to 2.9 hours. Concurrently, rainfall dips from 72mm (2.83") in September to 31mm (1.22") in November, paving the way for the approaching winter season.Winter weather in Thunder Bay
The winter period in Thunder Bay is characterized by severe cold temperatures, with average lows plummeting to -20.6°C (-5.1°F) in January. This season also welcomes the highest snowfall reaching a peak of 389mm (15.31") in December. The short and cloudy days offer limited sunshine hours, with daylight dwindling to its minimum at 8.4 hours in December, and sunshine hours dipping to 2.9 hours in December and January. Unquestionably, the winter in Thunder Bay is a season for enthusiasts of snow or cold weather adventurers.Weather in January
In Thunder Bay, Canada, January is the coldest month of the year. The temperature reaches as low as -20.6°C (-5.1°F) and it rarely rises above -8°C (17.6°F). The city also experiences its highest snowfall in this month, with an average of 365mm (14.37") of snow covering the ground. Weather in January »Weather in February
February weather in Thunder Bay carries on the cold trend from January. However, the snowfall decreases to 212mm (8.35") and temperatures slightly rise. The daylight hours start to increase, providing a hint of the approaching spring. Weather in February »Weather in March
The arrival of March signals the transition from winter to spring in Thunder Bay. Temperatures start to shift from extreme lows towards a more bearable range. The significant decrease in snowfall to 182mm (7.17") coupled with increased hours of sunlight signifies an end to the harsh winter. Weather in March »Weather in April
In April, the weather in Thunder Bay experiences noticeable warming. The last of winter’s snow melts away, replaced by increased rainfall at 37mm (1.46"). The longer hours of daylight accompanied by reduced snowfall facilitate the awakening of the city’s flora. Weather in April »Weather in May
May is the beginning of the warm season in Thunder Bay, with temperatures steadily climbing. However, the wettest period begins with rainfall peaking at 66mm (2.6"). The extended hours of daylight promote growth in the city's gardens, parks, and forests. Weather in May »Weather in June
June marks the summer arrival in Thunder Bay. It brings the greatest number of daylight hours and sees a rise in temperatures to a more summer-like range. The rainfall, however, continues to be high with 84mm (3.31") recorded on average. Weather in June »Weather in July
July is the warmest month in Thunder Bay, with temperatures reaching up to 24.3°C (75.7°F). Despite the heat, July also sees its fair share of rain with 87mm (3.43") on record. Nonetheless, the agreeable weather, combined with extended sunlight makes for ideal conditions for outdoor leisure activities. Weather in July »Weather in August
In August, the weather in Thunder Bay remains warm although it is slightly cooler than July. Rainfall reaches its peak this month at 90mm (3.54"). The long hours of daylight and warm temperatures continue to invite outdoor engagements, including communal festivals and events. Weather in August »Weather in September
September signals the onset of autumn in Thunder Bay. While rainfall decreases to 72mm (2.83"), temperatures begin to fall. The diminishing daylight hours highlight the ebbing of summer. Yet the city remains a draw with its stunning foliage transformation, a spectacle enjoyed by locals and visitors alike. September's arrival comes with a decrease in the average high-temperature, moving from a warm 23.3°C (73.9°F) in August to a comfortable 17.7°C (63.9°F). Weather in September »Weather in October
The weather in October in Thunder Bay continues the autumn trend initiated in September. Cooler temperatures become the norm and there's substantial rainfall. It's the start of the transition period towards much colder months. Autumnal activities such as pumpkin picking and leaf-peeping are popular during this time. The arrival of October in Thunder Bay signals a shift in temperature, down from a comfortable 17.7°C (63.9°F) in September to a chilly 9.9°C (49.8°F). Weather in October »Weather in November
November in Thunder Bay marks a definite transition from autumn to winter. As temperatures drop and snowfall increases to 265mm (10.43"), winter begins to set in. The diminishing daylight hours add a crisp chill to the air. With the arrival of the first significant snow, winter activities begin to take root. November is characterized by a clear drop in the average high-temperature, falling from October's frosty 9.9°C (49.8°F) to a cold 1.4°C (34.5°F). Weather in November »Weather in December
The weather in Thunder Bay in December is characterized by a full winter cloak. Temperatures fall significantly, and snowfall rises to 389mm (15.31"). This marks a return to the deep winter conditions experienced early in the year. Weather in December »Updated: Feb 5, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
January tends to be the coldest month in Thunder Bay, with temperatures averaging a daily high of -8°C (17.6°F) and a low of -20.6°C (-5.1°F).
The month with the least rainfall in Thunder Bay is January, when the rain falls for 0.6 days and typically collects 0mm (0") of precipitation.
Throughout the year, there are 92.6 rainfall days, and 547mm (21.54") of precipitation is accumulated.
Months with snowfall in Thunder Bay are January through May, September through December.
In Thunder Bay, during the entire year, snow falls for 62.7 days and aggregates up to 1631mm (64.21") of snow.
The months with the coldest seawater in Thunder Bay are January through April, with an average sea temperature of 2°C (35.6°F).
January, February, November and December, with an average maximum UV index of 1, are months with the lowest UV index in Thunder Bay.
On Sunday, 10. March 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from EST to EDT. Daylight Saving Time ends on Sunday, 03. November 2024, at 2:00 am, and the time zone reverts from EDT to EST.
June through August are months without snowfall in Thunder Bay.
June has the longest days of the year in Thunder Bay, Canada, with an average of 16h and 0min of daylight.
June has the most sunshine of the year in Thunder Bay, with an average of 8.7h of sunshine.
June and July, with an average maximum UV index of 7, are months with the highest UV index in Thunder Bay, Canada.
In Thunder Bay, Canada, the average highest temperatures are observed in July, with a high of 24.3°C (75.7°F) and a low of 11.1°C (52°F).
The month with the most rainfall in Thunder Bay, Canada, is August, when the rain falls for 12.3 days and typically aggregates up to 90mm (3.54") of precipitation.
August and September, with an average sea temperature of 13°C (55.4°F), are months with the warmest seawater in Thunder Bay, Canada.
The months with the least sunshine in Thunder Bay, Canada, are November and December, with an average of 2.9h of sunshine.
The month with the most snowfall in Thunder Bay, Canada, is December, when snow falls for 13.9 days and typically aggregates up to 389mm (15.31") of snow.
December has the shortest days of the year in Thunder Bay, with an average of 8h and 24min of daylight.
Average temperature
Thunder Bay, Canada
The warmest month (with the highest average high temperature) is July (24.3°C).
The month with the lowest average high temperature is January (-8°C).
- Average low temperature in January:
-20.6°C - Average low temperature in February:
-17.7°C - Average low temperature in March:
-10.7°C - Average low temperature in April:
-3.2°C - Average low temperature in May:
2.2°C - Average low temperature in June:
7.1°C
The month with the highest average low temperature is July (11.1°C).
The coldest month (with the lowest average low temperature) is January (-20.6°C).
Average rainfall
Thunder Bay, Canada
- Average rainfall in January:
0.4mm - Average rainfall in February:
2.9mm - Average rainfall in March:
16.1mm - Average rainfall in April:
36.6mm - Average rainfall in May:
66.3mm - Average rainfall in June:
83.5mm
- Average rainfall in July:
87mm - Average rainfall in August:
89.5mm - Average rainfall in September:
72mm - Average rainfall in October:
55.3mm - Average rainfall in November:
30.7mm - Average rainfall in December:
6.2mm
The wettest month (with the highest rainfall) is August (89.5mm).
The driest month (with the least rainfall) is January (0.4mm).
Average rainfall days
Thunder Bay, Canada
- Average rainfall days in January:
0.6 days - Average rainfall days in February:
1.1 days - Average rainfall days in March:
3.4 days - Average rainfall days in April:
7.1 days - Average rainfall days in May:
11 days - Average rainfall days in June:
13.8 days
- Average rainfall days in July:
12.9 days - Average rainfall days in August:
12.3 days - Average rainfall days in September:
13.5 days - Average rainfall days in October:
11 days - Average rainfall days in November:
4.7 days - Average rainfall days in December:
1.2 days
The month with the highest number of rainy days is June (13.8 days).
The month with the least rainy days is January (0.6 days).
Average snowfall
Thunder Bay, Canada
- Average snowfall in January:
365mm - Average snowfall in February:
212mm - Average snowfall in March:
182mm - Average snowfall in April:
103mm - Average snowfall in May:
10mm - Average snowfall in June:
0mm
The month with the highest snowfall is December (389mm).
The months with the least snowfall are June, July and August (0mm).
Average snowfall days
Thunder Bay, Canada
- Average snowfall days in January:
12.9 days - Average snowfall days in February:
9.6 days - Average snowfall days in March:
8.4 days - Average snowfall days in April:
4 days - Average snowfall days in May:
0.5 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0.3 days - Average snowfall days in October:
3.4 days - Average snowfall days in November:
9.7 days - Average snowfall days in December:
13.9 days
The month with the highest number of snowfall days is December (13.9 days).
The months with the least snowfall days are June, July and August (0 days).
Average sea temperature
Thunder Bay, Canada
The best months for swimming (with the highest average sea temperature) are August and September (13°C).
The coldest months (with the lowest average sea temperature) are January, February, March and April (2°C).
Average daylight / Average sunshine
Thunder Bay, Canada
- Average daylight in January:
8h and 54min - Average daylight in February:
10h and 12min - Average daylight in March:
11h and 54min - Average daylight in April:
13h and 42min - Average daylight in May:
15h and 12min - Average daylight in June:
16h and 0min
- Average daylight in July:
15h and 36min - Average daylight in August:
14h and 18min - Average daylight in September:
12h and 36min - Average daylight in October:
10h and 48min - Average daylight in November:
9h and 12min - Average daylight in December:
8h and 24min
The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 24min).
- Average sunshine in January:
3h and 30min - Average sunshine in February:
4h and 30min - Average sunshine in March:
5h and 12min - Average sunshine in April:
7h and 6min - Average sunshine in May:
8h and 24min - Average sunshine in June:
8h and 42min
- Average sunshine in July:
8h and 36min - Average sunshine in August:
8h and 18min - Average sunshine in September:
5h and 30min - Average sunshine in October:
4h and 0min - Average sunshine in November:
2h and 54min - Average sunshine in December:
2h and 54min
The month with the most sunshine is June (Average sunshine: 8h and 42min).
The months with the least sunshine are November and December (Average sunshine: 2h and 54min).
Average UV index
Thunder Bay, Canada
The months with the highest UV index are June and July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 1).
